The Arizona sheriff who has made headlines across the country for his tough stance on undocumented immigrants is expected to take the witness stand today amid allegations that his trademark immigration sweeps amounted to racial profiling against Latinos.

Lawyers who say that Maricopa County Sheriff Joe Arpaio’s office disproportionately singled out Latinos in the patrols accused him of launching some sweeps based on emails and letters that don’t allege crimes, but complain only that “dark-skinned people” are congregating in a given area or speaking Spanish.

A group of Latinos who say they have been discriminated against filed the civil lawsuit against the sheriff, who makes jail inmates sleep in tents and wrote an autobiography titled “America’s Toughest Sheriff.”